Definition: In this task, you're given an article and an answer. Your task is to generate the fill-in-the-blank question for this answer based on the given article. The blanks are always at the end of the question, and can be filled with more than one word or phrase.
Input: Article: Just before Mother's Day I purchased the Flex Belt for my mother to help her lose some weight. I wasn't sure if she was going to like the present but she seemed to love it. I saw the Flex Belt review on the Internet by chance and was very impressed with what I read. It seems that the Flex Belt is helping thousands of people achieve their weight loss goals. I asked my mother a few questions about the Flex Belt such as whether this product was easy to use, whether she felt painful while using it and the most important question was whether she lost any weight. She told me that it was so easy to use, and that even a child could operate it. She also said that in the first period of using this product she did feel that it was a little bit magical and she was pleased with the amount of weight she had lost. Over the past few years it seems that my fitness routine  has gone downhill . I used to enjoy going to my local gym to do a bit weight lifting, or enjoy meeting up with friends once a week for a game of soccer. Recently I noticed that I became a bit "round", so I have started to do some exercise by taking a thirty-to-forty-minute run every morning. I feel like the weight that I have put on especially around my midsection is slowly dropping off. Everyone knows the benefits of having a slim waist but it seems that we don't actually do anything about trying to achieve this. There are a few reasons for this, such as lack of time, not being motivated  enough, or not having enough money to join a gym. So this is the reason I think the Flex Belt is great to own. I am happy that my mum loves the present and because the product is working great for my mum, I've decide to get one for myself as well. 
 Answer: whether the Flex Belt worked well

The most important question the author asked her mother was   _  .